According to the law of conservation of matter, which chemical equation represents a possible chemical reaction? A. CaCO3 Fe2O3 B. 2Na + Cl2 2NaCl C. 4Fe + 3O2 C6H12O6 + 6O2 D. C6H12O6 + 6O2 CaO + CO2

The correct answer is:

B. 2Na + Cl2 - -> 2NaCl

In fact, this is the only reaction among the choices where the number of atoms of each element is conserved. In fact, we see that on the left we have 2 atoms of sodium and 2 atoms of chlorine, and on the right we have two molecules of NaCl, which means that we still have 2 atoms of sodium (Na) and 2 atoms of chlorine (Cl).